I think what you're seeing Alcor is the fact that the left thigh is MUCH longer than the right thigh, so it throws off the proportions a bit. Forshortening makes stuff closer to us larger but it also makes the object comming at us shorter.
I think if you shorten the rightleg about by half it'll look alot better.
(left/right as in us looking at it not his left/right)
Also, the pose of the legs doesn't quite give the feeling that I think you're going for here. relaxed legs like that give a feeling of lazyness/relaxing. I would at the very least take the left lower leg and position it straight up and down, it should give the picture a much better feeling of strength.
If it's supposed to be "lazy" or "relaxed" then i would change the expression on his face
Also, his left arm would be bent resting like that on a bent leg, having a straight arm makes it look like he's reaching out at something and not resting on his thigh/knee. there's also some foreshortening errors going on there. he's reaching out almost directly at the camera, the top of the arm would be seen more than the side, and most of it would be obscured by the hand/forearm. The right arm doesn't really look like it's supporting his weight at all, and it's kinda at an awkward angle to be resting on something, so maybe bring it in towards the torso a little more.
You have a very powerfull image happening here, the feeling comes through very strongly and overall the quality of the drawing is awsome. I hope to see this completed in the near future.
Edit: i hope you don't mind but I threw together a redline skeleton to show what I'm talking about a little better.
Redline (sorry about the quality of the lines, usually use my tablet but don't have it with me at the moment, so it's all mouse XD like drawing with a bar of soap.)